Random Misfire - Possible Ignition Coil?

[J-Speed Inc.]

Recently, my 2005 FZ6 has developed a random misfire at random times. I thought it was due to the cheap Autolite spark plugs I installed on the bike about 2k miles ago, but have since replaced them with the correct NGK CR9EK plugs. The misfire is still occurring at random times whether the bike is warmed up or cold.

I've done some research online and have found that the 2003 R6 has a known problem with the ignition coils shorting out which caused similar problems to what I am experiencing with my FZ.

Have any of you experienced this problem? If so, how were you able to test the coils to see if they are within spec?

I found this link which I thought was helpful:
Ignition Coil Help/Advice Needed : Yamaha R1 Forum

Any help would be greatly appreciated!

 

[Motogiro]

Almost sounds like a secondary voltage failure and being that it's random it might be better to get it on a scope to see the misfire. Is it failing enough that you know you'll see it on a scope? You won't be able to ring out the secondary with an ohm meter to find and intermittent secondary failure because the failure is probably occurring at high voltage. I would first pull all the insulators on the output and very carefully inspect for a pinhole or track mark. It might be almost impossible to see. Also wouldn't hurt to check all primary coil pack connectors. Intermittents are a bummer to find...Good Luck!

 

[philosopheriam]

Here's a trick for finding cracks in coils/wires that are causing misfires (due to a short to ground)

Take a test light and ground it to the engine block/frame. Then, pass the tip of the test light along each spark plug wire and coil - if theres a crack, it will immediately short to the test light and stall the engine.

Just an old automotive trick

Misfires can also be caused by a fuel pump that is cutting in/out - have you performed a fuel pressure test on your bike?

 

[TownsendsFJR1300]

Here's a trick for finding cracks in coils/wires that are causing misfires (due to a short to ground)

Take a test light and ground it to the engine block/frame. Then, pass the tip of the test light along each spark plug wire and coil - if theres a crack, it will immediately short to the test light and stall the engine.

Just an old automotive trick



Will that procedure fry the test light bulb having the high voltage (if its shorted) go thru it? I would think it'd light it up as well, at least momentarily..


BTW, excellent tip! We always checked for those kind of shorts in the dark, looking for sparks/arcing.. I like your procedure much better...

 

[philosopheriam]

Hmm... I have a high-voltage test light, so, I've never killed a bulb in it...

 

[Motogiro]

Hmm... I have a high-voltage test light, so, I've never killed a bulb in it...

I think I know what light you're talking about. It has a little neon that lights kind of an orange color and it has an inline resistor that makes it capable of with standing high voltage. I would imagine there's a digital version of that today.

 

[TownsendsFJR1300]

My test light is a regular 12 volt, filiment style bulb (like a side marker bulb for the older cars)....

Actually, if your some distance away it'll still light up, just work your way in closer.. Thanks for the great tip....

Scott

 

[J-Speed Inc.]

Almost sounds like a secondary voltage failure and being that it's random it might be better to get it on a scope to see the misfire. Is it failing enough that you know you'll see it on a scope? You won't be able to ring out the secondary with an ohm meter to find and intermittent secondary failure because the failure is probably occurring at high voltage. I would first pull all the insulators on the output and very carefully inspect for a pinhole or track mark. It might be almost impossible to see. Also wouldn't hurt to check all primary coil pack connectors. Intermittents are a bummer to find...Good Luck!

I'm going to try that. It's very annoying to get to the spark plug wires due to their location on this bike, but I seem to get better at putting the airbox on each time I take the bike apart! I will check the insulation for any cracks or scrapes which would cause arcing.

What gets me is it seems like whatever is causing the problem is causing the ignition to cut-out on all four cylinders at the same time. I know what it feels like when a cylinder or two stops firing on a multi-cylinder engine; when the problem occurs, the bike basically shuts down for a second then bucks back to life. The dash stays lit and no error codes are generated which would cause the check engine light to illuminate.

I was thinking I would do an Ohms-test on the coils near the battery to determine if they are in-spec. I downloaded a service manual for the FZ6 which will hopefully provide me with ohm readings for these coils. I wanna check as many things as possible while I have the bike apart!

 

[TownsendsFJR1300]

You may want to check your kickstand safety switch (take apart and clean the contacts-not hard to do). Its located next to the kickstand, just behind it... Also your clutch safety switch located on the left handle bar. You can squirt some WD 40 in there and clean up the connections without much fuss..

It sounds like your kickstand switch might be dirty telling the computer its down and to shut off. Its designed to do that. If the contacts are dirty the switch thinks the kick stand is down...

 

[Motogiro]

You may want to check your kickstand safety switch (take apart and clean the contacts-not hard to do). Its located next to the kickstand, just behind it... Also your clutch safety switch located on the left handle bar. You can squirt some WD 40 in there and clean up the connections without much fuss..

It sounds like your kickstand switch might be dirty telling the computer its down and to shut off. Its designed to do that. If the contacts are dirty the switch thinks the kick stand is down...

Also the Kill Switch. We just had a member have a failure with the kill switch. Jump the 2 wires on the kill switch and take it for a ride and see if the engine stops cutting out. Could even be the connectors are loose but best to make a jumper and tape it up and see if it runs normal.

Clutch safety switch is only during the starter crank cycle and will not affect engine once it is running.

 

[J-Speed Inc.]

You may want to check your kickstand safety switch (take apart and clean the contacts-not hard to do). Its located next to the kickstand, just behind it... Also your clutch safety switch located on the left handle bar. You can squirt some WD 40 in there and clean up the connections without much fuss..

It sounds like your kickstand switch might be dirty telling the computer its down and to shut off. Its designed to do that. If the contacts are dirty the switch thinks the kick stand is down...

Great tip! I will try that along with Motogiro's suggestion of the kill switch. I have already removed the clutch safety switch as it broke a few thousand miles ago. The connector has a small jumper wire inside it which eliminates the clutch safety switch.

Thanks for everyone's help! It's greatly appreciated! I will be trying these two suggestions this weekend after moving to a new apartment on Saturday.

 

[PcH]

I wish I found this thread or was told about it by the previous owner (J-Speed Inc.) before I purchased this bike because now I'm the one with this problem